Iceland's airspace temporarily closed down early Sunday because of a violent eruption of the country's most active volcano, the airport administration Isavia said.

"The status right now is that Keflavik airport, our biggest international airport, is closing. The airspace is closing," Isavia spokeswoman Hjordis Gudmundsdottir told AFP.

The airspace closure, she said, "affects pretty much all of Iceland right now, at least for the next hours. ... Flights to and from Iceland are shutting down."

The decision came after Grimsvoetn, Iceland's most active volcano located at the heart of its biggest glacier Vatnajoekull, began erupting late Saturday, sending a plume of smoke and ash as high as 20 kilometres (12 miles) into the sky.

Winds remained fairly calm Sunday, appearing to send the ash cloud north and northeast, potentially threatening flights routed to the north of Iceland, Gudmundsdottir said.

She said a new update on the situation was set for 1200 GMT.

Saturday's eruption began just over a year after the nearby Eyjafjoell volcano erupted, shutting down large swathes of European airspace for almost a month amid fears the volcanic ash could wreak havoc on aircraft engines.